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Discussion Starter · #1 ·
The 6.5" sub that came with my Philips HT in a box was slightly damaged. So I would like to make a box that would sound at least as good, maybe better.

Can I get some suggestions on box design for an 8" similar to or using a Dayton SD215A-88? Budget is low ($70?), but I plan to use the speaker output from the Philips BD player, so no amplifier. It is 1000W peak output total, so I would guess it can realistically push less than 200W to the sub. I don't need high volumes, just want to hear it and don't expect to rattle the walls.
 

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Welcome to HTS! :wave:

To clarify, you'd like to replace your passive subwoofer in your HTIB system? This should be doable. I would guess the clean power output of a sub channel of an HTIB would be in the 10-40W range, which isn't much, but is plenty if you aren't expecting wall rattles.

What are your size constraints? Does $70 include box materials, and are you planning on building a new box?

Something like the Dayton is just the right thing to be looking at. Once we answer some questions we can pick an ideal sub driver.
 

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Discussion Starter · #3 ·
Yeah, I'm replacing the box and driver. I'm not an audiophile by any means, so might have been satisfied with it. But the box was what was damaged, so it crackled. I took it apart and was pretty disappointed at how cheaply made it was and threw the whole thing out.

The area I want to put it is about 15" x 18" x 28"(h). Budget includes box materials.

Thanks for your help!
 

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If you could do about 14x17x21 with 5/8" MDF, with some dowels for bracing, that would work pretty nicely. Add a 3"x12" port and it would play real low. Specs would be 2.1cuft tuned to 25Hz, with the SD218A-88. I don't think the HTIB would over power it and it could even have a subsonic filter built in already, hard to say.

Did you check the broken HTIB sub driver to see that it was 4 ohms? That's an important detail so you don't risk overheating your HTIB receiver.
 

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Discussion Starter · #7 ·
Thanks for working that up Fusseli. I have downloaded the two versions of WinISD that I could find. Is that version available? I am an engineer by day, but have never dealt with audio really. Will take me some time to wrap my head around the concepts. Interesting though!

And back to Mike P.'s question about where the subsonic filter is: The manual for my HTIB says the sub freq response was 60Hz and up (forgot the upper end), so I suppose it is possible the filter is quite high. That might suck... :dontknow: My formal education is electronics, so I would pop the top on the BD player in a minute to see if I can mess with the filter.
 

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Sure thing. With a strong HPF that high, there's no reason for the large volume and low tune. Assuming a 3rd order 65Hz HPF, something like a 1.2 cuft box (14x14x15, 5/8" mdf) tuned to 40Hz (2"x3" round port) would do. Both files are attached.
 

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Discussion Starter · #11 ·
Ahh, two good options here! Now I'm learning a lot, and found a W6-1139SI on ebay.... Is the Tang Band that much better? Is it the Xmax that makes the big difference?
 

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Ahh, two good options here! Now I'm learning a lot, and found a W6-1139SI on ebay.... Is the Tang Band that much better? Is it the Xmax that makes the big difference?
The Tang Band allowed me to get the tuning I wanted in a much smaller enclosure, which was a hard requirement for me. If that is not the priority then you may get better bang for the buck with the Dayton 8".

All the options that have been presented will be a vast improvement over what you are replacing. Unfortunately, the built in high pass filter in your HTIB will handicap them quite a bit when it comes to reproducing the real low notes.
 

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With a 60Hz cutoff you might actually want to look at cheap efficient woofers vs. subwoofers.

The Bravox PXW10D-2 (on sale) in half a cubic foot sealed has an F3 of 61Hz and wil do 110dB with 200 watts. That would be dirt-easy to build and would drive a room a bit better than the 8" Dayton. If you ever got a real sub you could then put it in your car. :)

There is a two 4 ohm VC version if you need an 8 ohm load.
 

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Discussion Starter · #15 ·
Ok, what are the chances there is NO subsonic filter? I put a 4Ω dummy load on the subwoofer output and get a perfectly happy 2V (volume turned down a bit) @ 10Hz and starts to roll off @ around 140Hz.

So I think I'm going to go with a 1.2ft^³ box tuned to 40Hz... Stop me if I'm going the wrong direction by Saturday! Going to look for some MDF and order a 8" driver.
 

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Ok, what are the chances there is NO subsonic filter? I put a 4Ω dummy load on the subwoofer output and get a perfectly happy 2V (volume turned down a bit) @ 10Hz and starts to roll off @ around 140Hz.

So I think I'm going to go with a 1.2ft^³ box tuned to 40Hz... Stop me if I'm going the wrong direction by Saturday! Going to look for some MDF and order a 8" driver.
Are you going with the TB W6 or staying Dayton SD? And if there's no HPF, why not try the 2.1cuft @ 25 Hz instead of 1.2 @ 40? Unless the smaller size was an allure...
 

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Discussion Starter · #17 ·
Are you going with the TB W6 or staying Dayton SD? And if there's no HPF, why not try the 2.1cuft @ 25 Hz instead of 1.2 @ 40? Unless the smaller size was an allure...
Staying with the Dayton SD. The size is the allure. And I don't know how strong this addiction might get, lol! The smaller/higher box will certainly be immediately satisfying to me, and if I get a hankering for more, I can use this driver in a bigger box later. At that point I will have some experience, and more funds to upgrade the mains and receiver as well.
 

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Staying with the Dayton SD. The size is the allure. And I don't know how strong this addiction might get, lol! The smaller/higher box will certainly be immediately satisfying to me, and if I get a hankering for more, I can use this driver in a bigger box later. At that point I will have some experience, and more funds to upgrade the mains and receiver as well.
Sure thing!

Without any HPF, the 1.2cuft would be better with a slightly lower tune, like 33 Hz. Not sure if the HTIB will have enough power to bottom out the sub or not, you'll just have to wait and see. If it does you could try a passive HPF.

My calculations are a 14x14x16 box, 5/8" mdf, some minor dowel bracing, and a 3x12" round port. Something like a trimmed precision port would work perfect.
 

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Discussion Starter · #19 ·
Ok, here is what I have sketched up. 5/8" MDF is not readily available here, so might use 3/4". Constructive feedback welcomed. I think I'll move the port to one side so I can put a vertical support in the center.
 

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I suggested the thinner mdf because it's a low power sub, there will be no problem going heavier.

Nice CAD sketches! If it were me, I would make the front baffle a solid piece on the outside so you don't have to see all of the joints... Functionally it makes no difference. This will be an overbuilt box, but that's in fact a good thing for subs :)
 
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